Cathode ray tube



arch 6, 1945. HANNS-HEINZ WOLFF ZQ Q CATHODE RAY TUBE Filed Jan. 15, 1941 //71/ep far EQaienie 6, 1945 ATES PATENT OFFICE CATHODE RAY TUBE Application January 15, 1941, Serial No. 374,460

In G

4 Claims.

The present invention relates to cathode ray tubes in which means are provided for modulating the intensity of the stream between the oathode and an intercepting electrode (collecting plate) by deflection control with the aid of a cutting-off arrangement. Tubes and systems of this kind can be used as switching devices, socalled cathode ray relays, more particularly electron ray relays, and have been already described in the copending patent applications Ser. No. 96,582 (filed August 18, 1936) and Ser. No. 112,488 (filed November 24, 1936).

In employing such tubes one often desires to obtain the highest possible voltage impulses from the device. For this purpose one can connect the one of the taps for the impulses with the collecting plate, the other with the cutting-off diaphragm and insert a resistance between the two electrodes. If the diaphragm is provided with a fixed high potential, for example, i connected with the anode of the focusing system or, in a given case, is used itself as an anode, a very high drop of potential occurs at the resistance connected between the diaphragm and the collecting plate. This drop of potential can assume such values that the greater, or at least a considerable, part of the electrons which have passed through the diaphragm does not reach the collecting plate but is rejected and returns to the diaphragm. It is evident that by the way the obtainable amount of the voltage impulses is greatly limited.

The difiiculty in question can be avoided by giving the collecting plate the highest positive potential which preferably is so much higher than the potential of the diaphragm as is required by th amount of the desired voltage impulse.

. The advantage of the just mentioned arrangement, however, is partly compensated by the increased voltage requirement of the device, because voltage supplies must be provided which are able to furnish higher potentialsthan are required for operating the relay or the tube by itself. Further there is the danger that variations of the potential of the diaphragm cause considerable distortions of the field in front of the diaphragm and that thereby the precise-control of the relay is questioned.

It is an object of the present invention to provide arrangements and circuits in and for cathode ray tubes of the above mentioned type which make it possible to avoid the disadvantages of the known arrangements.

According to one feature of the invention, between the diaphragm and the collecting plate ermany January 19, 1940 there is provided an auxiliary electrode which is so dimensioned, shaped, and biassed, that practically all of the electrons which have passed through the diaphragm reach the collecting plate. The auxiliary electrode prevents that a considerable part of the electrons returns to the diaphragm.

The invention will be better understood with the aid of and further features of the invention will be apparent from the following more detailed description and the accompanying drawing of which, in a purely diagrammatic fashion and by way of example:

Fig. 1 illustrates an embodiment of the complete relay and some essential elements of the circuits connected thereto, while Figs. 2-4 show various embodiments of the arrangement comprising the cut-off diaphragm, the auxiliary electrode, and the collecting plate.

In Fig. 1 the reference numeral 1 designates the tube vessel which contains the incandescent cathode 2 and an electron-optical focusing system consisting, for example, of the Wehnelt cylinder 3 and the electrodes 4, 5, and 6. Element 5 is the main anode above referred to of the focusing system. Moreover, the figure shows two pairs 1 and 8 of deflecting plates mounted within the tube.

It may be noted that for a certain range of applications only means for deflecting the beam in one direction are required.

The tube further contains the cut-ofi' diaphragm 9 and the collecting plate Ill. The auxiliary electrode ll, provided according to the in-= vention, is mounted between the electrodes 9 and I0 and preferably in the closest possible vicinity of electrode 9. The auxiliary electrode is also given the form of a diaphragm. The shape of its aperture corresponds to the apertur of the cut-off diaphragm and is homologous to the latter. Preferably the aperture of diaphragm H is somewhat larger than the aperture of diaphragm 9 so that the field produced by the auxiliary electrode H does not noticeably penetrate into or through the aperture of 9.

The incandescent cathode 2 is heated by means of a current source l2. The potentials required for operating the tube are furnished by the voltage supply l3 which at the sam time provides for the biassing potentials of the several tube electrodes. The electrode ID, the variations of potential of which are to be utilised, is connected via a resistance I4 to the diaphragm 9. The voltage impulses preferably are tapped at the lowest potential which the electrode I is desired to assume in operation. In the example illustrated by Fig. 1, the auxiliary electrode is connected to the potential of the cathode, but in a given case it may be suitable to select the potential of the diaphragm l l higher or lower than the cathode potential.

The electron-optical system is so designed and the potentials of its electrodes are so adjusted that the electron ray is focused as sharply as possible in the plane of the boundary of the aperture of the diaphragm 9. For example, the focusing system may be so dimensioned as to concentrate the beam in across-over point situated in the aperture of the cut-oil diaphragm. The potential of the diaphragm 9 is made equal to anode potential and preferably even somewhat higher. This is indicated by the elements shown in dotted lines of battery l3 in Fig. 1.

Of course, the electrostatic electron-optical system shown in the drawing can be replaced by an electro-magnetic system or by combined electrostatic and electro-magnetic systems. It is also possible to employ a magnetic deflecting system or, when the beam is to be deflected in two directions, combined electrostatic and electromagnetic deflecting means instead of the electrostatic defleeting system of Fig. 1. Also an intensity control grid may be additionally provided in certain cases.

The field produced by the electron-optical focusing system and correspondingly the shape of the electrodes or at least of the apertures of the electrodes of the electron-optical system need not be of rotational symmetry. Instead of spherical electron-optical lenses, for example, electronoptical cylinder lenses can be used and preferably combined with a corresponding form of the emissive surface of the cathode.

In Figs. 2-4 several embodiments of the electrodes 9, l0 and H are illustrated.

Fig. 2 shows a diaphragm 9 provided with a tubular abutment which projects into the aperture of the auxiliary electrode ll.

Figs. 3 and 4 show diaphragms and auxiliary electrodes, the rims of which are bent over in order to avoid as far as possible the danger of breakdown between electrodes which have a high potential diiference with respect to one another. In such cases the leads to the electrodes preferably are fixed at the inner sides of the bent parts of the diaphragms-or at least at the inner sides facing away from one another of the electrodes.

Various shapes depending on the actual requirements can be given to the aperture of the diaphragm 9, for example the apertures can be made circular, slit-shaped, triangular or of still other form.

I claim:

1. In an electron relay arrangementin combination a cathode ray tube comprising means for producing a cathode ray, means including an apertured diaphragm and a collecting plate for performing a cut-01f control of said cathode ray between said diaphragm and said collecting plate, means for focusing said cathode ray sharply in the plane of the aperture of said diaphragm, an auxiliary apertured electrode mounted between said diaphragm and said collecting electrode in close vicinity of said diaphragm, the aperture of said auxiliary electrode being homologous to, at least as large as, and at the most somewhat larger than the aperture of said diaphragm, means for connecting said auxiliary electrode to a lower potential than both said diaphragm and said collecting electrode, and a tubular abutment put on the aperture of said diaphragm and projecting into the aperture of said auxiliary electrode.

2. In an electron relay arrangement in combination a cathode ray tube comprising means for producing a cathode ray, means including an apertured diaphragm and a collecting plate for performing a cut-off control of said cathode ray between said diaphragm and said collecting plate, means for focusing said cathode ray sharply in the plane of the aperture of said diaphragm, an auxiliary apertured electrode mounted between said diaphragm and said collecting electrode in close vicinity of said diaphragm, the aperture of said auxiliary electrode being homologous to, at least as large as, and at the most somewhat larger than the aperture of said diaphragm, at least the rims of said diaphragm and of said auxiliary electrode being bent over towards the sides turned away from each other of said two electrodes, and means for connecting said auxiliary electrode to a lower potential than both said diaphragm and said collecting electrode.

3. In an electron relay arrangement in combination a cathode ray tube comprising means for producing a cathode ray, a collecting plate, means including an apertured diaphragm performing a cut-off control of said cathode ray between said diaphragm and said collecting plate, means for focusing said cathode ray sharply in the plane of the aperture of said diaphragm, an auxiliary apertured electrode mounted between said diauhragm and said collecting electrode in close proximity of said diaphragm, the aperture of said auxiliary electrode being homologous to and slightly larger than the aperture of said diaphragm for reducing the penetration of the electric field between said diaphragm and said auxiliary electrode into the aperture of said diaphragm, means for further reducing such penetration, and means for connecting said auxiliary electrode to a lower potential than both said diaphragm and said collecting plate.

4. In an electron relay arrangement in combination a cathode ray tube comprising means for producing a cathode ray, means including an apertured diaphragm and a collecting plate for performing a cut-off control of said cathode ray between said diaphragm and said collecting plate, means for connecting said diaphragm to said collecting electrode via a resistance, means for focusing said cathode ray sharply in the plane of the aperture of said diaphragm, an auxiliary apertured electrode mounted between said diaphragm and said collecting electrode in close vicinity of said diaphragm, the aperture of said auxiliary electrode being homologous to and substantially as large as the aperture of said diaphragm, means for reducing the penetration of the electric fieldbetween said diaphragm and said auxiliary electrode into the aperture of said diaphragm, and means for connecting said auxiliary electrode to a lower potential than both said diaphragm and said collecting electrode.

HANNS-I-IEINZ WOLFF. 

